Process for preparing n, n-dialkyl-n&#39;-arylamidines



3,189,648 PROCESS FOR PREPARING N ,N-DIALKYL-N ARYLAMIDINES Henry J. Gerjovich, Wilmington, DeL, assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Apr. 11, 1962, Ser. No. 186,640 2 Claims. (Cl. 260564) Q is selected from the group consisting of halogen,

nitro and cyano;

Q and Q are selected from the group consisting of hydrogen, halogen and methyl;

Y is selected from the group consisting of hydrogen and methyl;

R and R can be the same or different and are each selected from the group consisting of methyl and ethyl; and when R and R are joined they become the divalent radical pentamethylene, tetramethylene or oxydiethylene; and when R and Y are joined they become the divalent radical trimethylene or tetramethylene.

The trisubstituted amidines in this invention are prepared by the reaction at atmospheric pressure and at slightly elevated temperatures of about 60 to 190 C. with an anhydrous aryl isocyanate having the formula:

wherein Q Q and Q have the same significance as in Formula 1, with an N,N-di-substituted amide of the formula wherein:

Y, R and R taken separately or together have the same significance as in Formula 1.

This reaction can be illustrated as below by the reaction of 3,-4-dichlorophenylisocyanate with dimethylformamide. The reaction produces N-(3,4-dichloropheny1)-N',N'dimethylformamidine.

3,189,648 Patented June 15, 1965 The reaction of an aryl isocyanate of Formula 2 with an N,N-disubstituted amide of Formula 3 is preferably eifected by heating the aryl compound in an excess amount of the amide at a temperature of from 70 to C. under atmospheric pressure until carbon dioxide no longer evolves from the mixture.

It is essential thatthe two reactants are interacted under anhydrous conditions. Traces of moisture will interact with isocyanates to form the corresponding urea compound as illustrated by the following series of equations wherein the Qs have the same'significance as in Formula 1:

NCO E20 2 @Nnooon Q3 It is preferred to use an excess of the given N,N-disubstituted amide reactant to avoid the formation of undesirable by-products, namely, the dimer and trimer of the reactant isocyanate. The following tabulation of data illustrates the importance of reacting the aryl isocyanate under dilute conditions with respect to the amide so that the isocyanate cannot react with itself. The result is economically practical yields of the desired trisubstitutedamidines.

TABLE I Percent Moles of Percent Percent Yield of Run amide Solvent O02 yield isocyanate No. evolved amidine dimer and;

trimer 1. 0 Toluene..- 5.0 93. 0 1.0 None. 30.0 27. 7 62.0 2. 0 64. 0 48. 9 38. 3 4. 0 79. 0 70.0 Trace 5. 0 95. 0 90.0

One mole of the phenylisocyanate is used in all the reactions tabulated above. The reactions in Table I are heated at reflux temperature until carbon dioxide ceases to evolve. In Run #1, essentially pure phenylisocyanate trimer (M.P. 285 C.) crystallized out of the toluene solvent.

In Runs 2 through 5, unreacted dimethylformamide is recovered by distillation under convenient reduced pressure. Continued distillation gives pure N-phenyl- N,N-dimethyl-formamidine and the remaining pot residue when triturated with ether, gives dimer and trimer of phenylisocyanate.

The trisubstituted amidines are alkaline and are generally clear distillable liquids or low melting solids slight- 1y soluble in Water but very soluble in such solvents as ether, benzene and chloroform.

The compounds of the invention are useful as herbicides, especially against Johnsongrass at a dosage of about from reaction mixture by distillation under reduced pressure. The distilled pot residue is extracted With ether. The ether is removed from the extract by evaporation to give a 99% yield of ether-free product consisting of N- 10 pounds per acre; and as corrosion inhibitors for acid (p-chloro-phenyl)-N',N-dimethylformamidine. solutions on metal. They can also be employed as addi- Analysrs.-Calcd as C H CIN N, 15.34; Cl, 19.45. tion agents in electroplating; for instance, they can be Found: N, 15.05; Cl, 19.51. added to cadmium or zinc cyanide baths at the limit of E l 2 their solubility to produce desirable deposits. mm? c In order that the invention may be better understood, A solution of 1 part anhydrous dimethylformamide the followmg specific illustrative examples are given in and 1 part p-chlorophenylisocyanate is added gradually addltion to those already above indicated. Unless otherwith stirring to 1 part of dimethylformamide maintained wise indicated, parts are by weight. at reflux temperature. The carbon dioxide evolution is Example 1 thus simple to lead off and its rate of evolution is easy I to control. The entire reaction mixture is maintained iN "hmethylfmmamldmm at reflux until carbon dioxide is no longer evolved. At this point the reaction is distilled to remove the excess 01- N ON(CHs)e dimethylformamide. Essentially pure N-p-chlorophenyl- N',N-dimethylformamidine remains as the pot residue, Fifteen and four-tenth parts of p-chlorophenyl-isoand d1stillat1on of this residue under convenient reducedcyanate and 36.5 parts of anhydrous dimethylformamide pressure gives pure product in over 90% yield. are combined, mixed and heated gradually until a steady E l 3 h h 21 stream of carbon dioxide gas evolves from the reaction xamp as t mug mixture. Heating of the reaction mixture is continued so The procedure of Example 1 is used to prepare the that the temperature of the amide-lsocyanate mixture is amidines listed in column 4 of Table II. In columns maintained at or slightly below its reflux temperature 2 and 3 of Table II are listed the reactants and theuntil carbon dioxide ceases to evolve from the reaction amount of each employed. All temperatures are degrees mixture. The excess amide reactant is then removed centigrade.

TABLE II Analysis Example Isoeyanate and parts Amideand parts Trisubstituted amidine obtained, B1. or Ml. Calculated Found No. by weight used by weight used and empirical formula N Cl N Cl 3 m-Chloropheuyliso- Dimethylformamide N-(m-ehlorophenyl)-N,N-dimeth- 102103/.22 mm.-. 15.34 19.45 '15. 26 20.06 eyanate (15.4). (36.5). ylfgmcalmNidine yield) 15. 20 20.08

9 ll 2- 4 o-Chlorophenylisodo N-(o-chlorophenyl)-N,N-dimeth- 99-102/.25 mum--. 15.34 19.45 15.34 19.40 eyanate (15.4). ylfplrmcalmNidine (58% yield) 15.16 19. 47

9 ll 2. 5 3,4-dichlorophenyl- .do N-(3,4-dichlorophenyl)-N,N-di- 133135/.25 mm 12.91 32.2 12.79 32.69

isoeyanate (18.8). rleltlhyflonamidine (60% yield) 12.79

9 10 Z 2- 6 m-Chlorophenyliso- N,N-dimethylacet- N-(m-ehlorophenyl)-N,N-dimeth- 96-97/.28 mm 14.25 18.08 13.87 18.42 cyanate (15.4). amide (43.0). ylaeetamidine (54% yield) 18. 34

OwHlsClNj. 7 3,4-diehlorophenyl- .d0 N-(3,4-dichlorophenyl)-N,N'-di- 12.10 30.3 11.98 31.25

isoeyanate (18.8). mcthylacetamidine- (36% yield) 12. 26

CmHIlgNzClz. 8 do N,N-diethylf0rma- N-(3,4-diehlorophenyl)-N,N-di- 132/.15 n1rn 11.42 28 97 11. 52 28.85 mide (50.5). ethyliormamidine (90% yield) 11.40 28. 60

CnHuClgNg. 9 do N,N-diethy1acet- N-(3,4-diehlorophenyl)-N,N-di- 143/.5 mnL-.. 10 81 27.41 10.73 27.83 amide (57.5). ethylacetamidine (46% yield) 27. 91

CmHmClzNg. 10 3,5-diehloro-4-rneth- Diinethylformamlde N-(3,5-dichloro-4-methylphenyl)- ylpheuylisoeya- (36.5). N,N-dimethyliormamidiue nate (20.2). CwHigClgNg. 11 p-Nitrophenylisocy- N-iormylmorpho- 4-(p-nitrophenylimino-methyl) 112.5114

nate (16.4). line (57.5). morpholine (77% yield) CnH sNsOs. 12 o-Nitrophenylisoey- Dimethylformamide N-(o-nitrophenyl)-N,N-dimethyl- 152154/1.0 mm.-.

anate (16.4). (36.5). formamidine (75% yield) 0 11 10 13 m-Nitrophenylisodo N-(m-nitrophenyl)-N',N-dimethy1- 58.5-59.5"

cyan-ate 16.4). iormamidine (32% yield) CDHHNROZ. 14 4,5-dichloro-2-nitro d0 N-(4,5-dichloro-2-nitrophenyl)- 126.5127.5 16.03 27.09 15.55 26.78 phenylisocyanate N ,N'-dimethylforrnamidine 15. 36 26. 79

3. (48% yield) 0931901319302. 15 2,4,6-trichlorophendo N-(2,4,6-triehlorophenyl)-N,N- 73-735 11.14 42.84 11.04 41. 77

ylisoeyanate dimethylformamidine (75% yield) (22.2). V CgHpClgNz. 16 3,4-diehlorophonyl- N-aeetylruorpho- 4-[1-(3,4-diehlorophenylumno) 10.25 26.00 9.72 26.92 isocyanate (18.8). line (64.5). ghlyllhgorlghgline (43% yield) 9.94 26. 72

l2 l4 2 2 o 17 do N-methylpyrroli- 2-(3,4-diehloropheuyliruino) 1- 11.52 29.21 11.10 29.02 done (49.5). riethylplylr rrolidiue (55% yield) 11.22 28. 61

11 12 2 2' 18 do N-iormylmorpho- 4-1(3,4-dichlorophenylimino)methyl] 164166/.4 111111..-. 10.98 27.84 10.91 27.34

line (57.5). morpholine (68% yield) 11.08

CuHgClzNzO- 19 o-Chlorophenylisodo 4-[(0-ehloropheny1imino) methyll- 139142/.04 mm.-. 12.69 16.09 12.65 15.63

eyanate (15.4). n10rHplg 11iue0(58% yield) 12. 75

l 20 do N-aeetylmorpho- 4-[1- (ehlordpheuylimino) ethyl] 138-142/0.3 rum.-. 11.94 15.13 12.12 15. 65

line (64.5). morpholiue (57% yield) 12.29

CnI'IuC] g '21 3,4-dlcl1lorophenyl- N-methylpiperidone 2-(3,4-diehl orophenylim1no)-1- isoeyauate (18.8). (56.5). metliylpipcrldine.

6 The invention claimed is: R and R taken separately are each selected from the 1. The process which comprises mixing under anhydrous group consisting of methyl and ethyl; conditions at atmospheric pressure at a temperature within and when R and R are joined they are together selected the range from about 70 to 180 C. a compound of the from the group consisting of pentarnethylene, tetraformula: 5 methylene and oxydiethylene; and when R and Y are Q1 joined they are together selected from the group conl.- sisting of trimethylene and tetramethylene.

-No0 3Q 2. The process which comprises mixing under anhydrous conditions at atmospheric pressure at a temperature withwith from 1 to molar parts as much of a compound of 10 in the range f to C. one part by Weight of the formula! p-chlorophenylisocyanate and 2 parts by weight of dimethylformamide to form N-p-chlorophenyl-N',N'-d i o=o-N methylformamidine. Y I

Y R2 References Cited by the Examiner 1 to produce a compound of the formula:

Q Bredereck et al.: Ber. Deut. Chem, vol. 92, pp. 837-849 1959).

Knott et al.: J. Org. Chem, vol. 14, pp. 879-885 1949) I Kuhn: Ber. Deut. Chem., vol. 18, pp. 1476-1479 Q3 Y 2 (1885). wherein: Roherts et al.: J.A.C.S., vol. 73, pp. 2277-2281 (1951). Q is selected from the group consisting of hydrogen, wfimerz Chan" 245-6 (1960)- chlorine and HMO; 2 Wiley: J.A.C.S., vol. 71, pp. 3746-3748 (1949). Q and Q are each separately selected from the group consisting of hydrogen, chlorine and methyl; CHARLES PARKER Primary Examiner Y taken separately is selected from the group consisting L. ZITVER, Examiner.

of hydrogen and methyl; 

1. THE PROCESS WHICH COMPRISES MIXING UNDER ANHYDROUS CONDITIONS AT ATMOSPHERIC PRESSURE AT A TEMPERATURE WITHIN THE RANGE FROM ABOUT 70* TO 180*C. A COMPOUND OF THE FORMULA: 